Abstract
On-orbit lunar calibration is common for trending instrument gain over time. This requires a model of lunar spectral irradiance; usually the ROLO model developed in 2005 and which is now known to have significant limitations. The SLIM (Spacecraft and earth-base Lunar Irradiance Model) software system is designed to combine as many surface, high-altitude and space-based measurements of lunar irradiance as available. Until high-accuracy sole-source traceable measures of lunar spectral irradiance are made covering the 5 dimensions of photometric geometry, this may be the best approach to developing an improved lunar calibration model. The process of acquiring a lunar image and converting it to apparent irradiance has received less attention than needed to approach the potential of lunar calibration. I hope to create a mindset not of %, but sub-ppt; the Moon itself is good to sub-ppm! To approach the full potential of lunar calibration, we need to improve the guidelines and the practice of acquiring lunar images and converting them to irradiance, accumulate lunar irradiances from many sources, and produce a collaborative lunar model that accounts for solar variation. Considering the current and potential uncertainties of all the steps, there is no barrier to reaching 100 ppm in lunar calibration for trending and 1 ppt for comparison between instruments.
Seeking a Consensus Evolutionary Lunar Calibration Model, Many Observations, One Moon
On-orbit lunar calibration is common for trending instrument gain over time. This requires a model of lunar spectral irradiance; usually the ROLO model developed in 2005 and which is now known to have significant limitations. The SLIM (Spacecraft and earth-base Lunar Irradiance Model) software system is designed to combine as many surface, high-altitude and space-based measurements of lunar irradiance as available. Until high-accuracy sole-source traceable measures of lunar spectral irradiance are made covering the 5 dimensions of photometric geometry, this may be the best approach to developing an improved lunar calibration model. The process of acquiring a lunar image and converting it to apparent irradiance has received less attention than needed to approach the potential of lunar calibration. I hope to create a mindset not of %, but sub-ppt; the Moon itself is good to sub-ppm! To approach the full potential of lunar calibration, we need to improve the guidelines and the practice of acquiring lunar images and converting them to irradiance, accumulate lunar irradiances from many sources, and produce a collaborative lunar model that accounts for solar variation. Considering the current and potential uncertainties of all the steps, there is no barrier to reaching 100 ppm in lunar calibration for trending and 1 ppt for comparison between instruments.